Werner Erhard's highly successful est cult is partly derived from Scientology. Erhard had some experience with Scientology in 1969. Then he worked for a while in Mind Dynamics, itself an offshoot of Jose Silva's Mind Control.

Est (Erhard Seminars Training) has been a singularly successful synthetic derivation, which has itself gone on to generate new movements, transmitting aspects of Scientology thought or practice far from the domain of L. Ron Hubbard.

1992 July 21, Ray Clancy, “Professionals fall prey to New Age gurus”, in The Times, United Kingdom:

Werner Erhard, a former used-car salesman, founded his Erhard Seminar Training system (EST) in 1971. He drew upon many sources in the development of his philosophy including Zen Buddhism, Dale Carnegie's Positive Thinking, L. Ron Hubbard's Scientology and Jose Silva's Silva Mind Control. Erhard's seminars were at first 60-hour courses over two weeks designed to give insights into the meaning of life; his philosophy has been described as 'the most important of the self religions' that developed in the 1970s and 1980s.

EST (Erhard Seminars Training), a therapeutic movement founded by Werner Erhard (Jack Rosenberg), a salesman, and based on consciousness training programs and psychology-of-success literature. EST was incorporated as an educational corporation and employed techniques drawn from Scientology, Zen, Dale Carnegie, and humanistic psychology; thus it accommodates elements associated with oriental mysticism to the American success ethic. EST was widely criticized for sanctifying selfishness and for abrasive and traumatic training sessions. Highly successful in the late 1970s, EST was later officially discontinued and replaced by a new organization, the Forum. See also North America, new religions in.

L. Ron Hubbard repackaged Scientology from occultism, and est/Forum was a repackaging of Scientology by Werner Erhard, but few Scientologists or estians ever see the connections, and both leaders seem to have gained little from their teachings. This is what the followers of Erhard found so unsettling; he was the great pop artist of spirituality, yet was unable to apply his insights to himself.

...the human potential and psychotherapy movements, as well as the more 'life-affirming' New Religious Movements and religions of the self. This was the complex world of the Californian 'psychobabble', of Scientology and est (Erhard Seminars Training, later called Forums Network), of Encounter Groups, meditation techniques and self-help manuals designed to assist individuals 'realise their potential'.